<?php
require_once 'db_conn.php'; 
header("content-type:text/html;charset=utf-8");

$username = $_POST['username'];
$password = $_POST['password'];

$sql = "
    select *
    from user
    where account='$username'
        and password='$password'
    limit 1;
    ";
$result = $conn->query($sql);
if($result->num_rows>0){
    echo "正确！";
}else{
    echo "用户名或密码错误！";
}